1. Field of the Invention
The present invention generally relates to the provision of high speed telecommunication services. In particular, the present invention relates to a system and a method for the quality status analysis of an access network of a fixed network supporting broadband telecommunication services. More in particular, the present invention relates to a system and a method for the quality status analysis of a Copper Access Network supporting broadband services based on a xDSL technology (“generic Digital Subscriber Line”).
2. Description of the Related Art
The exponential increase in the popularity of the Internet and of related data services has prompted service providers in the Public Switched Telephone Network (PSTN), to seek new technologies to deliver high speed data services to their customers. One solution is provided by DSL (Digital Subscriber Line) technologies. Several DSL technologies offer high speed services over existing copper facilities commonly referred to “subscriber loops”. Such technologies include ADSL (“Asymmetrical Digital Subscriber Line”); HDSL (“High-bit-rate Digital Subscriber Line”); RDSL (“Rate Adaptive Digital Subscriber Line”); SDSL (“Symmetric Digital Subscriber Line”); and VDSL (very High-speed Digital Subscriber Line”). These DSL or similar technologies are collectively known as “xDSL” services.
A problem encountered in the provision of xDSL services is that subscriber loops have largely been neglected from a technology upgrade perspective. Existing subscriber loops and the structure of the copper distribution network were originally designed for narrow band voice telephony and not to support high speed data services. Consequently, the electrical characteristics of the cables and subscriber loops set limits to the provision of broadband services: for example, many subscriber loops include wire gauge changes and bridged taps (unused extension lines) which limit the available bandwidth, limiting the performance of the loops with respect to the delivery of an xDSL service.
U.S. Pat. No. 6,266,395 discloses a method and an apparatus for single-ended qualification of subscriber loops for xDSL services. The method involves first screening a subscriber loop database for disqualifying devices or services, associated with that loop, which are incompatible with xDSL services. If none are found, a set of predetermined electrical characteristics of the subscriber loop are derived from information in the database, or directly measured using test equipment at a central office end of the subscriber loop. The electrical characteristics are used to calculate an available bandwidth for xDSL services on the subscriber loop.
WO 01/13609 teaches loop qualification methods and systems for qualifying an ADSL loop which involve evaluating Loop Make-Up (LMU) data to determine whether loops are qualified for certain services, such as ADSL services or other digital services. The LMU data includes such information as whether the loop is comprised of copper, fibre, it is a DLC (“Digital Loop Carrier”), its length, resist zone, carrier zone, loading factor, the existence of a DAML (“Digital Added Main Line”) and taper code information. The loop qualification methods and systems obtain LMU data on existing loops as well as information on loops which have not yet been completed. Network service providers (NSP) interface with the loop qualification systems to determine whether certain lines are qualified for a service. Loop qualification systems also include web-based interfaces to allow both NSPs and end users to make an inquiry as to the capability of a given loop.
The Applicant has observed that a network operator's ability to obtain a degree of knowledge that is punctual, updated and evolving over time of the potential of its own access network critically depends on the ability to integrate and mutually correlate information about the structure of the network, the number and type of systems installed thereon and the transmissive characteristics of the network itself. Whilst network structure and the number and type of installed systems are typically described in appropriate databases (Network Inventory) normally contained and updated within computerised databases, the transmissive characteristics of the network are generally not available locally but only on a statistical basis as the national or regional level.
In particular, the transmissive characteristics of the copper network do not depend only on the physical characteristics (e.g. the electrical capacity) and topological characteristics (e.g. the length) of the single subscriber loop, but also on the degree of electromagnetic coupling between the loop and the surrounding environment. In particular, in the case of the xDSL transmission systems using bandwidth bands from a few kHz to a few tens of MHz, the actual transmissive capacity available on the loop supporting the xDSL services is also limited by the other transmissive systems (homologous or “legacy”, for instance HDB3 or ISDN-BA) operating on the loops present in the same cable sector, whose transmitted signals, by proximity effect, are coupled by crosstalk on the loop in question, constitute a significant interference to the transmission.